1 files changed, 51 insertions, 0 deletions
diff --git a/scripts/make_preview_image.lua b/scripts/make_preview_image.lua
new file mode 100755
index 0000000..6bcaac8
--- /dev/null
+++ b/scripts/make_preview_image.lua
@@ -0,0 +1,51 @@
+#!/usr/bin/lua
+
+local filename = ...
+local name = filename:match("([^\\/]+)%..*$")
+
+
+-- get colors
+local text = io.open(filename):read("*a")
+local colors = {}
+for r, g, b in text:gmatch("#(%x%x)(%x%x)(%x%x)") do
+  r = tonumber(r, 16)
+  g = tonumber(g, 16)
+  b = tonumber(b, 16)
+  table.insert(colors, { r, g, b })
+end
+
+table.sort(colors, function(a, b)
+  return a[1] + a[2] + a[3] < b[1] + b[2] + b[3]
+end)
+
+local function eq(a, b)
+  return a[1] == b[1] and a[2] == b[2] and a[3] == b[3]
+end
+
+local prev = {}
+for i = #colors, 1, -1 do
+  if eq(colors[i], prev) then
+    table.remove(colors, i)
+  else
+    prev = colors[i]
+  end
+end
+
+
+--generate svg file
+local w = 200
+local h = 16
+local fp = io.open("previews/" .. name .. ".svg", "wb")
+
+fp:write('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="'..w..'" height="'..h..'" shape-rendering="crispEdges"> \n')
+
+for i = 1, #colors do
+  local width = w/#colors
+  local r, g, b = table.unpack(colors[i])
+  local rect = '<rect x="'..(i-1)*width..'" width="'..width..'" height="'..h..'" fill="rgb('..r..', '..g..', '..b..')"></rect> \n'
+  fp:write(rect)
+end
+
+fp:write('</svg>')
+fp:close()
+